The invention relates to optical disk players, and more particularly, to pickup head circuits in optical disk players.
Optical disks, such as a compact disk (CD) or a digital versatile disk (DVD), are widely used in electronic equipment for recording and reproducing audio and video information in a high density format. CDs may be used as a recording medium for storing audio information in a high density format. DVDs may be used as a recording medium for storing video information, since a DVD can store more information in a higher density format than a CD.
To meet various requirements for recording information in a high density format and reproducing it, various kinds of CDs and DVDs have been developed. For example, as optical disks of a CD-group, a CD read-only memory (CD-ROM) disk, a CD-recordable (CD-R) disk, and a CD re-writable (CD-RW) disk have been developed. As optical disks of a DVD-group, a DVD-ROM disk for using a read only memory, a DVD-recordable (DVD-R) disk, a DVD re-recordable (DVD-RW) disk, and a DVD re-writable (DVD-RAM) disk have been developed.
In order to write and read information to and from each of the various types of optical disks, a pickup head comprising an infrared laser diode is required. Conventionally, laser diodes used in optical disk players are driven by current and would be damaged easily when suffering unexpected large current. Thus, it is important to protect laser diodes from unexpected large current in order to maintain normal operations of optical disk players.